A variety of closures have been proposed over the years for use with containers wherein the closures include a lid connected to a body with a living hinge and wherein the lid moves between the open and closed positions with a snap-action effect. Although such closures may work generally satisfactorily for the service for which they were designed, there are applications in which a large number of open-close cycles of operation involving large movements or high stresses may cause the closures to fail with prolonged use.
Also, living hinges used for snap-action closures are typically molded as unitary structures from synthetic thermoplastic material. In some applications, a closure must be fabricated from materials from which an acceptable living hinge cannot be fabricated Further, in some applications, it would be beneficial to provide a closure lid and closure body made from dissimilar materials.
It would thus be desirable to provide a snap-action type closure that does not require a living hinge structure. This would permit a greater variety of materials to be used, and would permit the closure lid and body to be made in different colors
Some designs have been proposed for closures which can be self-maintained in an open position and/or a closed position and wherein the lid and body are separate pieces. With some such designs, it may be relatively easy for the lid to be removed from the body, either accidentally or intentionally. However, in certain applications it would be desirable to provide an improved two-piece closure which would be relatively inexpensive to manufacture and relatively easy to assemble but which could not be easily disassembled. Such a non-removable lid would be a desirable feature in, for example, tamper-proof or tamper-evident closure designs.